Hi Fernando, first of all congratulation for your great job and thanks to share it with us!
I come to the problem, my diy controller freezes once a day every day. The first days it appened on the morning (7/8 am) the last days on the afternoon/evening (18 pm). At the moment it controls only leds, water temperature, and main tank level (w/out ato) but will improve once i solve this issue.
When the controller freezes i push reset button and the "please insert sd card" message appear, the only way is to disconnect power supply and reconnect. Once done there is a bug on date something like "XXXX de XXXX de 2150" and time "27:xx:xx" (or inexistent hours) this just for a minute or less, then it start work properly. But the day after freezes again.
Maybe a problem with sdcard reading? Seems it lose connection with it (the error message after reset). I've got many problem with w5100 shield and sdcard conflict so at the moment i'm not using it.
I've also a suggestion for other users having problem with sd card, the sd card i use (a 2gb transcend) wasn't recognized by ferduino until i formatted it with Sd Formatter tool: Sd Formatter hope this can be useful.
Bye
R.